so it was easier to determine whether the latch was insecure? Paint the latch in orange or another high contrast colour?
Not sure that helps, I seem to recall a post on a much earlier thread about this issue that the problem was that when the cowls were open the dangling latch was a nuisance and was sometimes pushed flush to get it out of the way. Then the cowls get closed but unless someone immediately opens the latch, engages and re-latches them it can appear to a quick glance that all is closed and latched whereas they aint.
Have to say it sounds to me like the latch design is the problem here, classic Human Factors issue?